85 
firmly attached it could not change position but itmust grow. In 
fungus, at the same time preserving the external appearance of 
in which it grew was relatively wide and the planks rough. An- 
other specimen which grew in a very thin space and between 
smooth-planed boards resembles a fine quality of kid in both ap- 
pearance and to the touch. 
The fungi thus far considered are either parasitic or ee 
in mode of life ; we now come to a series which form le 
dent group, namely the lichens. These plants are symbiotic ; 
each lich ists of a fung i an alga living together, each one 
nourishing the other. Many people know a lichen by its exter- 
nal appearance ; but relatively few know its very int ng st! 
ture and mod i The structure of lichens is well illustrated 
drawn, while many of the species which grow on stones and rocks, 
ipy the shelves of the exhibi- 
as well as ot 
tion cases. 
The exceedingly curious class of plants known by the formid- 
We have a series of well-executed plates which illustrate ‘ie 
